Out with the old, in with the new.
Uninstall 2007 before you install 2010. Why are you doing this, there is not
much difference in the two -- perhaps some bug fixes, that sort of thing. If
you have more applications in your 2007 Suite that come in 2010, I suggest
that 2007 is better. If you get a needed application in 2010 that 2007 does
not have, then by all means do the upgrade. Otherwise, leave well enough
alone and use the money to take your Main Squeeze for a night on the town.